Conventionally, for example, module-type electronic circuit devices are used in card edge-type engine control units (ECU) of motorcycles and the like. As the electronic circuit devices, for example, electronic circuit devices each including a circuit substrate that has electronic components mounted thereon and has one end portion in which a terminal section is formed and a resin sealing member that seals the circuit substrate with the terminal section being exposed are known (for example, see Patent Document 1).
By inserting the terminal section into an insertion port of a connector and connecting the terminal section to a connector-side terminal section, such an electronic circuit device is used. In the electronic circuit device, when the terminal section is inserted into the insertion port, the resin sealing member is brought into contact with a sealing member arranged over the whole periphery of the insertion port. At this time, the sealing member is brought into tight contact with the whole periphery of the resin sealing member, thereby blocking the penetration of external moisture to the inside of the connector.
The electronic circuit device, as illustrated in FIG. 4, is manufactured by arranging the circuit substrate 2 inside a cavity portion 32 of a metal mold apparatus 31 and filling the cavity portion 32 with a resin. The metal mold apparatus 31 is formed by an upper die 33 and a lower die 34. The upper die 33 includes: a first hollow portion 35 having a shape following an outer shape of the tipper half part of the resin sealing member; and a second hollow portion 36 that is arranged to be connected to the first hollow portion 35 and houses the upper half part of the terminal section 5. In addition, the lower die 34 includes: a third hollow portion 37 having a shape following an outer shape of the lower half part of the resin sealing member; and a fourth hollow portion 38 that is arranged to be connected to the third hollow portion 37 and houses the lower half part of the terminal section 5.
The circuit substrate 2 is arranged inside the cavity portion 32 in a state in which an O-ring 10 is fitted to the boundary portion between a portion in which electronic components 4 are mounted and the terminal section 5. In such a case, the O-ring 10 is brought into tight contact with the upper die 33 on the boundary portion between the first hollow portion 35 and the second hollow portion 36 and is brought into tight contact with the lower die 34 on the boundary portion between the third hollow portion 37 and the fourth hollow portion 38. As a result, the cavity portion 32 is formed by the first hollow portion 35, the third hollow portion 37, and the O-ring 10. In addition, while the terminal section 5 is arranged inside a space 39 that is formed by the second hollow portion 36 and the fourth hollow portion 38, the O-ring 10 arranged between the space 39 and the cavity portion 32 blocks the penetration of a resin into the space 39, and accordingly, the terminal section 5 is not sealed with the resin.
The electronic circuit device can be acquired by opening, the metal mold apparatus 31 and extracting the electronic circuit device after the resin filled in the cavity portion 32 is solidified. At this time, the O-ring 10 is bonded to the solidified resin. In addition, in the electronic circuit device, as a trace of the boundary between the upper die 33 and the lower die 34, a parting line is formed along the side face of the circuit substrate 2.